The present invention relates to optical computing devices and, more particularly, to using discriminant analysis techniques and processing with optical computing devices in order to reduce the time required for determination of chemical and/or physical properties of a substance.
In the oil and gas industry, it can be important to determine precisely the characteristics and chemical compositions of fluids circulating into and out of subterranean hydrocarbon-bearing formations. Typically, the analysis of fluids related to the oil and gas industry is conducted off-line using laboratory analyses, such as spectroscopic and/or wet chemical methods, which analyze an extracted sample of the fluid. Depending on the analysis required, however, such an approach can take hours to days to complete, and even in the best-case scenarios, a job will often be completed prior to completion of the analysis.
Off-line, retrospective analyses can further be unsatisfactory for accurate determination of fluid characteristics, because the characteristics of an extracted sample of the fluid often change during the lag time between collection and analysis, thereby rendering the measured properties of the sample non-indicative of the true chemical composition or characteristic. Factors that can alter the characteristics of a fluid during the lag time between collection and analysis can include, for example, scaling, reaction of various components in the fluid with one another, reaction of various components in the fluid with components of the surrounding environment, simple chemical degradation, and bacterial growth.
Furthermore, accurate off-line laboratory analyses of a fluid sample can sometimes be difficult to perform because of unknown contaminants. For example, the collection of the sample in the field is typically obtained using a probe-type tool. However, it is difficult to know with certainty that the sample obtained is virgin formation fluid, rather than formation fluid contaminated with drilling fluid. While analyses of a fluid sample consisting solely of formation fluid may be accurate, a contaminated fluid sample is more likely to render inaccurate data. Although off-line retrospective analyses of a fluid can be satisfactory in certain cases, there are several drawbacks to such methods where a real-time or near real-time analysis would otherwise be a more effective method.